#!/usr/bin/env python
# -*- coding: utf-8 -*-


def sum(x, y, z):
    return x + y + z


if __name__ == '__main__':
    # 如下两种调用方式的意义相同
    ret1 = sum(1, 2, 3)
    ret2 = sum(y=2, z=3, x=1)

    print("return of sum( 1, 2, 3):", ret1)
    print("return of sum( y = 2, z = 3, x = 1):", ret2)
